JPH0814307A - Frequency sensitive buffer - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a frequency-sensitive shock absorber that can set low damping force characteristics independently on the extension side and the compression side, can reduce the number of parts and simplify the structure, and can reduce the cost. [Structure] Expansion / compression low damping valve has stud 2 on the outer peripheral side.
2 and a collar 25, and an expansion side orifice plate 2 having a compression side orifice hole 26a in the middle portion.
6 and a double-effect disc plate 24 which is provided so as to cover the pressure side orifice hole 26a by being overlapped with the inner peripheral side upper surface of the expansion side orifice plate 26. The opposing surface of the stud 22 has an inner peripheral side thereof. Is provided with an extension side seat surface 22e with which the inner peripheral upper surface of the double-effect disc plate 24 abuts, and an annular groove 22d which allows the outer peripheral side of the double-effect disc plate 24 to bend within a predetermined range. An annular stepped portion 25c is formed to allow the two-sided disc plate 24 and the expansion-side orifice plate 26 to bend on the inner peripheral side within a predetermined range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency-sensitive shock absorber that automatically changes damping force characteristics in response to the stroke frequency of the shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a frequency sensitive buffer, for example, one disclosed in Japanese Patent Laid-Open No. 3-181633 is known.

In this conventional shock absorber, a piston that defines the inside of the cylinder into an upper chamber and a lower chamber is fixed to the tip of a piston rod, and the piston is opened during the extension stroke so that the fluid chambers can communicate with each other. The expansion side high damping valve and the compression side high damping valve that is opened during the pressure stroke to allow communication between the fluid chambers are provided, and it is possible to communicate between both chambers by bypassing the both high damping valves below the piston. A cylindrical case forming a part of a bypass flow passage is formed, and the bypass flow is slidable in the housing in response to the fluid pressure difference and the frequency of the defined chamber in the hollow portion of the case. A frequency sensitive member that includes a spool that changes the cross-sectional area of the passage, a low-extension side damping valve that opens on both ends to allow communication between both chambers during extension, and a valve that opens at pressure stroke to communicate between both chambers. Possible pressure side low damping valve And a low damping force generating member comprising a valve body which is the intended incorporated in series, the valve body or the like is incorporated in a state of being attached to the stud.

That is, a stud having a small-diameter portion integrally formed with a through hole at its axial center is used in the central portion of the lower surface of the large-diameter disk forming the compression side retainer. On the other hand, from the top, the lift side regulating pressure side retainer, lift washer determining washer, pressure side low damping valve,
The valve body, low expansion side damping valve, washer for lift fulcrum determination, and expansion side retainer for lift amount regulation are installed and finally tightened with nuts, and the lower end of the cylindrical case is caulked on the lower surface of the outer periphery of the valve body. Thus, the low damping force generating member and the frequency sensitive member are housed and fixed in the case.

[0005]

However, in the conventional shock absorber as described above, the pressure side low damping valve and the extension side low damping valve are independently provided on the upper and lower end surfaces of the valve body. Therefore, a washer for determining the lift fulcrum and a retainer for controlling the lift amount must be provided separately on the compression side and the extension side, which increases the number of parts of the low damping force generating member and also increases the number of parts of the stud and the valve body. There is a problem in that the cost is high because the shape is complicated and the machining is troublesome.

The present invention has been made by paying attention to the conventional problems as described above, and the low damping force characteristics can be set independently on the extension side and the compression side as in the conventional example. It is an object of the present invention to provide a frequency-sensitive shock absorber capable of reducing the number of parts and the structure and simplifying the cost.

[0007]

In order to achieve the above-mentioned object, in the frequency-sensitive shock absorber of the present invention, a piston that defines the inside of the cylinder into an upper chamber and a lower chamber is fixed to the tip of a piston rod. The piston is provided with an expansion side high damping valve capable of communicating between the two fluid chambers by opening during the extension stroke and a compression side high damping valve capable of communicating between the two fluid chambers during opening of the pressure stroke, A hollow portion that forms a part of a bypass flow path that bypasses both the high damping valves and can communicate between the fluid chambers is formed in the cylindrical case provided in the lower portion of the piston, and the hollow portion is formed in the hollow portion. Is a frequency sensitive member including a spool that slides in the housing in response to a fluid pressure difference between both fluid chambers and the frequency to change the cross-sectional area of the bypass flow passage, and both fluid chambers are opened during the extension stroke. A low-extension-side damping valve that can communicate between A frequency-sensitive shock absorber in which a low damping force generating member including a valve body provided with a pressure side low damping valve capable of communicating between both fluid chambers and being opened during a pressure stroke is incorporated in series, The valve body is
An upper annular member and a lower annular member, which are axially opposed to each other, communicate with the lower chamber side in the axial center portion thereof, and have axial center holes for transmitting the fluid pressure of the lower chamber side to the frequency sensitive member. A sandwiching annular projection is formed on the outer peripheral side on the opposing surface of the upper annular member, and an annular seat surface that is lower than the sandwiching annular projection is formed on the inner peripheral side, and between the annular projection and the annular seat surface. An annular groove that is lower than the annular seat surface is formed in the outer peripheral surface of the upper annular member, and an axial cutout portion that communicates between the annular groove and the bypass channel is formed in the outer peripheral portion of the upper annular member. On the surface, a clamping annular projection is formed on the outer peripheral side, and an annular step portion lower than the clamping annular projection is formed on the inner peripheral side, and the expansion side low damping valve and the compression side low damping valve have the outer peripheral side facing upward. It is clamped and fixed between the annular projections of the annular member and the lower annular member. In addition, an annular large-diameter disc plate having a through-hole penetrating in the axial direction is provided at a substantially middle portion in the radial direction, and the through-hole is closed by being overlapped with the inner peripheral side upper surface of the large-diameter disc plate. The upper surface on the inner peripheral side is constituted by an annular small-diameter disk plate that contacts the annular seat surface.

[0008]

[Operation] When the piston strokes, the fluid flows between the upper chamber and the lower chamber, and at that time, a large flow resistance at the time of opening the compression side or expansion side high damping valve and the fluid flowing through the bypass passage Flow is restricted by the flow resistance of the throttle portion by the spool and the small flow resistance when opening the inner peripheral side of the small diameter disc plate and the large diameter disc plate or the outer peripheral side of the small diameter disc plate. A damping force is generated according to the flow resistance.

The damping force characteristic can be automatically changed by the fluid flow rate in the bypass passage, that is, by the position of the spool sliding in response to the fluid pressure difference between the upper chamber and the lower chamber and the frequency. it can.

That is, at the time of low damping force characteristics in which the bypass flow path is open, in one stroke of the shock absorber, the damping force due to the flow resistance at the time of opening the inner peripheral side of the small diameter disc plate and the large diameter disc plate. In the other stroke of the shock absorber, the damping force is generated by the flow resistance when the outer peripheral side of the small-diameter disc plate is opened, so that a low damping force characteristic is obtained between the extension side and the compression side. Can be set independently.

Also, the lift amount of the small diameter disc plate and the large diameter disc plate is regulated by the annular groove and the annular step portion which are respectively formed on the facing surfaces of the upper annular member and the lower annular member which constitute the valve body. Therefore, it is not necessary to separately provide parts such as a washer for determining the lift fulcrum and a retainer for restricting the lift amount, and the axial center hole, the notch, the annular groove, the annular stepped part, and the axial center hole. Since the roads and the like can be easily formed without requiring complicated processing, the cost is reduced by reducing the number of parts and simplifying the structure.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the embodiment will be described. FIG. 1 is a sectional view of an essential part showing a frequency sensitive buffer according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a cylindrical cylinder, and a piston 3 is fastened to a small diameter portion of a lower end of a piston rod 2 by a nut 8.
The interior defines an upper chamber A and a lower chamber B.

A compression side damping valve 3a is provided on the upper surface of the piston 3 to open and generate a damping force during a compression stroke, while the lower surface of the piston 3 is opened to generate a damping force during an expansion stroke. A side damping valve 3b is provided. The damping valves 3a and 3b are disk valves whose inner peripheral sides are fixed. The piston rod 2 is formed with a bypass hole 2a that bypasses the damping valves 3a and 3b and connects the chambers A and B.

At the lower end of the nut 8, a cylindrical case 1 for accommodating a mechanism for changing a damping force characteristic described later.
The upper end of 1 is connected and fixed by projection welding. A large-diameter hole (hollow portion) 11a communicating with the bypass hole 2a is formed inside the case 11. Inside the large-diameter hole 11a, the retainer 12 and the extension side check plate 14 are arranged in this order from above. , Expansion side constant plate 15, expansion side seat plate 16, spool housing 17, compression side seat plate 18, compression side constant plate 19, compression side check plate 20, retainer 21, stud (upper annular member constituting the valve body) 22, expansion pressure A dual-purpose disc plate (small-diameter disc plate) 24, an expansion-side orifice plate (large-diameter disc plate) 26, a collar (a lower annular member that constitutes the valve body) 25 are mounted, and the lower end of the case 11 is attached to the collar 25. By caulking to the lower surface of the outer periphery,
All of the above members are assembled in a state of being sandwiched between the lower surface of the nut 8 and the crimped portion 11b.

More specifically, the spool housing 17 is formed in a cylindrical shape with a spool hole 17a formed in the axial center thereof, and a large diameter hole 11 is formed in the middle of the outer peripheral surface thereof.
An annular protrusion 17b is formed on which a seal ring 29 for sealing the inner peripheral surface of a is mounted.

The retainer 12 has a central hole 12a formed in the central portion of a thin plate material, and a cutout portion 12b formed at equal intervals in the circumferential direction on the outer peripheral portion thereof. A plurality of leg pieces 12c each of which is bent downward.

As shown in FIG. 2, the extension side check plate 14 has an annular outer peripheral fixing portion 14b formed by forming a notched annular hole 14a in a thin flexible plate material, a part of which is left. And a circular valve portion 14c at the center and a connecting portion 14d that connects the two.

As shown in FIG. 3, the expansion side constant plate 15 has a central hole 15 having a diameter smaller than that of the valve portion 14c of the pressure side check plate 14 in the central portion of the thin plate material.
a is formed, and an arc-shaped elongated hole 15b is formed along the circumferential direction at a position facing the notched annular hole 14a of the pressure side check plate 14 on the outer periphery of the central hole 15a. The intermediate portion and the central hole 15a are connected by a narrow cutout portion 15c.

Returning to FIG. 1, the expansion side seat plate 16
Has a central hole 16a having a diameter smaller than that of the central hole 15a of the pressure side constant plate 15 in the central portion of the thick plate material. Further, the extension side check plate 14, the extension side constant plate 15, and the extension side seat plate 16
Is formed to have the same diameter as the spool housing 17, and is provided with the outer peripheral portion thereof being sandwiched and fixed between the retainer 12 and the upper opening end surface of the spool housing 17. Further, the retainer 12 is provided in a state in which the tip ends of the leg pieces 12c are inserted into the upper annular space 17c formed between the case 11 and the spool housing 17.

That is, as shown in FIG. 4, the seat surface a ₁ with which the valve portion 14c abuts is formed on the upper surface of the opening edge of the central hole 15a in the extension side constant plate 15, and the opening width w (of the cutout portion 15c is formed. (See FIG. 3) and the thickness h ₁ of the expansion-side constant plate 15 form an expansion-side cutting diaphragm b ₁ .

Next, returning to FIG. 1, the retainer 21, the pressure side seat plate 18, and the pressure side constant plate 1
9 and the compression-side check plate 20 have the same shape as the retainer 12, the expansion-side seat plate 16, the expansion-side constant plate 15, and the expansion-side check plate 14 described above, respectively, and only the retainer 21 corresponds to the retainer 12 and the retainer 12. The pressure side cutting diaphragm b ₂ is formed in the same manner as in the above case by being assembled in the reverse direction.
The details of the pressure-side constant plate 19 and the pressure-side check plate 20 are denoted by the reference numerals corresponding to those in FIGS. 2 and 3, and the description thereof is omitted.

Then, the above-mentioned pressure side seat plate 18,
The pressure side constant plate 19 and the pressure side check plate 20 are provided with the outer peripheral portion thereof being sandwiched between the lower opening end surface of the spool housing 17 and the retainer 21.

The retainer 21 has a leg piece 1
It is provided in a state in which the tip portion of 2c is inserted into a lower annular space 17d formed between the case 11 and the spool housing 17.

The stud 22 and the collar 25 constitute a valve body, which are axially opposed to each other. FIG. 5 is an exploded perspective view thereof, and FIG. 6 is an enlarged sectional view thereof. As shown, a small diameter shaft hole 22a is formed in the shaft center portion of one stud 22, and the other collar 2
A large-diameter shaft center hole 25a is formed in the shaft center part of 5, and
At the center of the lower surface of the stud 22, a boss portion 22b is formed which is inserted into the axial center hole 25a while leaving an annular flow path 25b between the stud 22 and the axial center hole 25a. Then, the outer peripheral edge portion of the stud 22 has four cutout portions 22c for forming a flow path at four locations.
Are formed.

Further, on the opposing surfaces of the stud 22 and the collar 25, an annular groove 22d and an annular stepped portion 25c for communicating between the passage forming cutout portion 22c and the annular passage 25b.
Are formed. That is, the annular groove 22d of the stud 22
Is an annular extension side seat surface 22e on the outer periphery of the boss portion 22b.
And the outer peripheral holding portion (holding annular projection) 22f of the expansion side orifice plate 26 is left on the outer peripheral side, and the outer peripheral side is communicated with the cutout portion 22c.
Further, the annular step portion 25c of the collar 25 has an outer peripheral holding portion (holding annular protrusion) 25d of the expansion-side orifice plate 26 left on the outer peripheral side thereof, and the entire inner peripheral side is lowered by one step to make the inner peripheral side annular. It is formed so as to communicate with the flow path 25b.

Then, in the state where the annular groove 22d and the annular stepped portion 25c are closed between the facing surfaces of the stud 22 and the collar 25, the double-effect disc plate 2 for both expansion and compression.
4 and the expansion-side orifice plate 26 are provided.
That is, the double-effect disc plate 24 also for expansion and the expansion-side orifice plate 26 are formed in an annular shape and are provided in a state of being overlapped with each other.
26 has the same inner diameter, and the outer diameter has an expansion side orifice plate 26.
Is formed to have a larger diameter, and the annular stepped portion 25c of the collar 25 is provided at a substantially central position in the radial direction of the expansion-side orifice plate 26 at the overlapping portion with the double-effect disc plate 24.
Four pressure side orifice holes (through holes) 26a communicating with the above are formed.

Further, the expansion side orifice plate 26 has its outer peripheral side on both outer peripheral sandwiching portions 2 of the stud 22 and the collar 25.
It is sandwiched and fixed between 2f and 25d, and the inner peripheral side is provided so as to be flexible in the direction of the annular step 25c of the collar 25. The upper surface of the peripheral edge is the extension side seat surface 2
It is provided in contact with 2e.

That is, the flow path forming cutout portion 22c, the annular groove 22d, the extension side orifice hole 26a, and the annular step portion 25.
c and the annular flow path 25b form a flow path forming a part of a bypass flow path G described later, and this flow path is opened / closed by the double-effect disk plate 24 and the expansion-side orifice plate 26 also for expansion. It is closed as much as possible. That is, as shown by the alternate long and short dash line arrow in FIG. 5 and the left half cross-sectional view in FIG. 6, when the fluid flows from the cutout portion 22c toward the annular flow path 25b in the extension stroke, A flow path (bypass flow path G) is formed by bending the inner peripheral sides of the dual-effect disk plate 24 also for expansion and the expansion-side orifice plate 26 with the peripheral edge as a fulcrum toward the annular step 25c (downward) of the collar 25. Open again
As shown by the chain double-dashed line arrow in FIG. 5 and the right half cross-sectional view in FIG. 6, the cutout portion 22 extends from the annular flow path 25b in the pressure stroke.
For the fluid flow in the c direction, the extension side seat surface 25d
The compression side orifice hole 26
The flow path (a bypass flow path G) passing through a is kept open. In other words, the upper surface of the expansion-side orifice plate 26 with which the lower surface of the outer peripheral edge of the double-effect disk plate 24 that also serves as the expansion surface abuts constitutes the compression-side seat surface. And
The annular step portion 25c serves as a lift restricting retainer that restricts the flexure of the inner peripheral portions of the double-sided disc plate 24 and the expansion-side orifice plate 26, and the annular groove 22d.
The bottom part of the double-sided disk serves as a lift restricting retainer for restricting the flexure of the outer peripheral part of the double-acting disc plate 24.

In the spool housing 17, a plurality of extension-side ports 17e that vertically connect the upper annular space 17c and the spool hole 17a with an annular protruding portion 17b interposed therebetween and a lower annular space 17d and the spool hole 17a that communicate with each other. A plurality of pressure side ports 17f are formed. A spool 31 is provided in the spool hole 17a so as to define an extension-side pressure receiving chamber D ₁ and a compression-side pressure receiving chamber D ₂ on both upper and lower sides thereof and to be vertically slidable.

Therefore, in the expansion side pressure receiving chamber D ₁ , the bypass hole 2a, the central hole 12a, the notched annular hole 14a, the elongated hole 15b,
Notch portion 15c (drawing side cut diaphragm b ₁ ), central hole 15
a, the fluid pressure on the upper chamber A side can be transmitted through the extension side transmission path M passing around the central hole 16a. On the other hand, the fluid pressure on the lower chamber B side can be transmitted to the pressure side pressure receiving chamber D ₂ via the pressure side transmission path N passing through the shaft center hole 25a, the shaft center hole 22a, and the pressure side cutting diaphragm b ₂ . . The extension side pressure receiving chamber D ₁
Fluid can be quickly returned to the upper chamber A side by opening the circular valve portion 14c through 15a, and the fluid in the pressure side pressure receiving chamber D ₂ can be returned to 19a by opening the circular valve portion 20c.
It can be quickly returned to the upper chamber A side via.

An annular groove 31a is formed on the outer peripheral surface of the spool 31 to connect the ports 17e and 17f at the neutral position of the spool 31, and the upper edge side of the annular groove 31a and the extension side port 17e. The expansion side variable throttle H is formed, and the compression side variable throttle K is formed by the lower edge side of the annular groove 31a and the compression side port 17f.

That is, the bypass hole 2a and the upper annular space 17
c, extension side port 17e, extension side variable throttle H, annular groove 31
a, the pressure side variable throttle K, the pressure side port 17f, the lower annular space 17d, the notch 22c, the annular groove 22d, the double-ended disc plate 24 and / or the extension side orifice plate 26, the annular stepped portion 25c, and the annular flow passage 25b. A bypass flow path G that connects the upper chamber A and the lower chamber B is formed. Therefore, the bypass flow passage G is configured such that either the expansion side variable throttle H or the compression side variable throttle K is throttled by sliding of the spool 31 to narrow the flow passage cross-sectional area. The spool 31 is elastically held by the upper and lower centering springs 32 and 33 at a neutral position in which both variable diaphragms H and K are fully opened.

As described above, the member between the retainer 12 and the retainer 21 constitutes the frequency sensitive member S, and the member between the stud 22 and the collar 25 constitutes the low damping force generating member T. There is.

Next, the operation of the embodiment will be described. When the piston 3 strokes, the fluid flows between the chambers A and B, and at that time, passes through the damping valves 3a and 3b, and when the fluid flows through the bypass flow passage G, the variable throttles H, The passage is restricted by passing through the double-effect disc plate 24 for both K and expansion and / or the expansion-side orifice plate 26, whereby a damping force is generated.

The damping force characteristic changes depending on the amount of fluid flowing through the bypass passage G, that is, the position of the spool 31. That is, the fluid pressure in the upper chamber A and the lower chamber B can be transmitted to the extension side pressure receiving chamber D ₁ and the pressure side pressure receiving chamber D ₂ via the extension side transmission passage M and the pressure side transmission passage N.

Therefore, the spool 31 makes a stroke due to the fluid pressure difference between the two chambers, whereby the cross-sectional area of the variable throttles H, K formed in the middle of the bypass flow passage G changes and the damping force characteristics change. That is, as shown in FIG.
When 1 is in the neutral position, both variable throttles H and K are in the fully open state, and at this time, as shown in the left half sectional view of FIG. The inner peripheral edge portions of the double-effect disc plate 24 and the expansion-side orifice plate 26 are opened, or the outer peripheral edge portion of the double-effect disc plate 24 is opened on the pressure stroke side as shown in the right half sectional view of FIG. The lowest damping force characteristic is obtained by allowing the fluid to flow through the valve. When the spool 31 strokes up or down, the expansion side variable throttle H (or the compression side variable throttle K) is closed, so that the fluid flow in the bypass passage G is completely stopped. By opening the damping valve 3a or the expansion-side high damping valve 3b and allowing the fluid to flow, the highest damping force characteristic is obtained.

Since the cut diaphragms b ₁ and b ₂ are formed in the middle of both the transmission paths M and N, the above-mentioned fluid pressure is transmitted at the time of low-frequency vibration, whereby the spool 31 is moved. Although the stroke is changed to a high damping force characteristic, at the time of high frequency vibration, the diaphragms for cutting b ₁ and b ₂ are cut.
Since the transmission of fluid pressure is cut by, the spool 31
Stroke is stopped, whereby the low damping force characteristic state is maintained.

As described above, the frequency-sensitive shock absorber of the embodiment has the stud 22 that constitutes the valve body.
And the annular groove 2 formed on the opposing surfaces of the collar 25 and the collar 25, respectively.
The lift amount of the double-effect disc plate 24 and the extension-side orifice plate 26 is regulated by the 2d and the annular step portion 25c. Therefore, parts such as a washer for determining the lift fulcrum and a retainer for regulating the lift amount are separately provided. There is no need, and the shaft center hole 22a and the cutout portion 22 are not necessary.
Since the c, the annular groove 22d, the annular stepped portion 25c, the shaft center hole 25a, etc. can be easily formed without requiring troublesome processing, it is possible to reduce the cost by reducing the number of parts and simplifying the structure. It has the feature of becoming.

Further, the low damping force characteristic on the extension side is determined by the double-effect disc plate 24 and the orifice plate 26 on the extension side, whereas the low damping force characteristic on the compression side is determined only by the double-effect disc plate 24. Therefore, similar to the conventional example, the low damping force characteristic can be set independently on the extension side and the compression side.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific structure is not limited to this embodiment, and there are design changes and the like within the scope not departing from the gist of the present invention. Also included in the present invention.

For example, in the embodiment, the double-acting disk plate 24 that also serves as the pressure-expanding member and the expansion-side orifice plate 26 are each composed of a single disk valve, but one or both of them may be composed of a plurality of disk valves.

[0042]

As described above, in the frequency-sensitive shock absorber of the present invention, the valve bodies are opposed to each other in the axial direction, and the axial center portion is communicated with the lower chamber side so that the frequency is the same. It is composed of an upper annular member and a lower annular member having an axial hole for transmitting the fluid pressure of the lower chamber side to the sensitive member, and a sandwiching annular protrusion is formed on the outer peripheral side on the opposing surface of the upper annular member. An annular seat surface lower than the sandwiching annular projection is formed on the inner peripheral side, an annular groove lower than the annular seat surface is formed between the annular projection and the annular seat surface, and the outer peripheral portion of the upper annular member is formed. Is formed with an axial cutout portion that communicates between the annular groove and the bypass flow passage, the lower annular member has a facing annular protrusion formed on the outer peripheral side, and an inner peripheral side formed with a sandwiching annular protrusion. The extension side low damping valve is formed with an annular step portion lower than the annular projection for use. And the compression-side low-damping valve is clamped and fixed on the outer peripheral side between both clamping annular projections of the upper annular member and the lower annular member, and has an annular large opening having a through-hole penetrating in the axial direction at a substantially middle portion in the radial direction. Diameter disc plate, and an annular small-diameter disc plate that is provided in a state in which the through hole is closed by being overlapped with the inner peripheral side upper surface of the large diameter disc plate and the inner peripheral side upper surface abuts on the annular seat surface. By adopting this means, it is possible to set the low damping force characteristics independently on the extension side and the compression side as in the conventional example, and it is possible to reduce the number of parts of the low damping force generating member and simplify the structure. Therefore, it is possible to reduce the cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a frequency-sensitive shock absorber according to an embodiment of the present invention.

FIG. 2 is a plan view showing an extension side check plate.

FIG. 3 is a plan view showing an extension side constant plate.

FIG. 4 is an enlarged view of a P portion of FIG.

FIG. 5 is an exploded perspective view showing a low damping force generating member portion.

FIG. 6 is an enlarged cross-sectional view for explaining the action of the low damping force generating member portion.

[Explanation of symbols]

A Upper chamber B Lower chamber S Frequency sensitive member T Low damping force generating member G Bypass flow path 1 Cylinder 2 Piston rod 3 Piston 3a Pressure side high damping valve 3b Extension side high damping valve 11 Case 11a Large diameter hole (hollow part) 17 Spool Housing 22 Stud (upper annular member that constitutes the valve body) 22a Shaft center hole 22c Cutout portion 22d Annular groove 22e Extension side seat surface 22f Outer peripheral holding portion (holding annular protrusion) 24 Both-effect disc plate (small diameter disc plate) 25 Collar (lower annular member that constitutes the valve body) 25a Shaft center hole 25c Annular groove 25d Outer peripheral holding portion (holding annular projection) 26 Extension side orifice plate (large diameter disk plate) 26a Pressure side orifice hole (through hole) 31 Spool

Claims (1)

[Claims] 1. A high-expansion-side damping, which defines an upper chamber and a lower chamber in a cylinder, is fixed to a tip of a piston rod, and the piston is opened during an extension stroke so that both fluid chambers can communicate with each other. A valve and a pressure side high damping valve that is opened during the pressure stroke and is capable of communicating between the two fluid chambers are provided, and both fluids are bypassed in the cylindrical case provided at the lower part of the piston by bypassing the both high damping valves. A hollow portion is formed which constitutes a part of a bypass flow passage capable of communicating between the chambers, and the inside of the hollow portion slides in the housing in response to a fluid pressure difference between both fluid chambers and a frequency to cause the bypass flow. A frequency-sensitive member that includes a spool that changes the cross-sectional area of the passage, a low-damping valve on the extension side that can be opened to communicate between both fluid chambers during the extension stroke, and a valve that can be opened to communicate between both fluid chambers during the pressure stroke Pressure side low damping valve A frequency-sensitive shock absorber in which a low damping force generating member including a lube body is incorporated in series, wherein the valve body faces in the axial direction and the axial center portion communicates with the lower chamber side, It is composed of an upper annular member and a lower annular member having an axial hole for transmitting the fluid pressure of the lower chamber side to the sensitive member, and a sandwiching annular protrusion is formed on the outer peripheral side on the opposing surface of the upper annular member. An annular seat surface lower than the sandwiching annular projection is formed on the inner peripheral side, an annular groove lower than the annular seat surface is formed between the annular projection and the annular seat surface, and the outer peripheral portion of the upper annular member is formed. Is formed with an axial cutout portion that communicates between the annular groove and the bypass flow passage, the lower annular member has a facing annular projection on the outer peripheral side thereof, and an inner peripheral side thereof with the clamping annular projection. Forming an annular step lower than the annular protrusion for The low-damping valve and the compression-side low-damping valve are clamped and fixed on the outer peripheral side between both clamping annular projections of the upper annular member and the lower annular member, and have a through hole penetrating in the axial direction at a substantially middle portion in the radial direction. An annular large-diameter disc plate,
The large-diameter disc plate is provided with the through hole closed by being overlapped with the inner-peripheral-side upper face of the large-diameter disc plate, and the inner-peripheral-side upper face is constituted by an annular small-diameter disc plate that contacts the annular seat surface. Frequency sensitive shock absorber.